Thud when Up-shifting
 

Anyone have any idea what might cause my issue?
When I Up-shift, it feels like something is slamming into the car. Noise and Feel comes from back of the car.

When I blip the throttle just before releasing clutch, the shift is smooth and it's not as noticeable.

Thanks for your input.

Ken

broken diff mount

Thanks for pointing to the right direction.

I changed the Diff Mount bushing with Superpro Poly and that problem of clunking is gone. Now to solve other noises under the car...

check the propshaft isn't loose
check your ppf isn't cracked or loose
if the above ok, could be internal issue with the gearbox.